In a bowl, mix together 2 cups of ice-cold buttermilk and 1 teaspoon of pure vanilla.
Add 2 ½ cups of all-purpose flour, 1 teaspoon of baking powder, 2 teaspoons of cinnamon, and 2 teaspoons of nutmeg to the buttermilk mixture and stir until well combined.
In another bowl, combine the 2 roasted sweet potatoes with ¼ cup of brown sugar, 1 stick of melted butter, a splash of vanilla, 2 teaspoons of cinnamon, and 2 teaspoons of nutmeg, mixing thoroughly.
Melt the remaining stick of butter and pour half of the biscuit dough into a baking dish.
Spread half of the sweet potato mixture over the biscuit dough, then layer the remaining biscuit dough on top, followed by the rest of the sweet potato mixture.
Use a knife to swirl the mixtures together gently, then cut into portions.
Bake in a preheated oven at 350°F for about 30 minutes.
